Heat treating furnace



March 7, 1939.

E. G. DE CORIOLIS HEAT TREATING IUmmmafl Filed July 3, 1937 3Sheets-Sheet-l (Ittomeg Patented Mar. 7, vr1939 l HEAT TREATING FURNACEErnest G. de Coriolis, Toledo, Ohio, assignor to Surface CombustionCorporation,

Toledo,

8 Claims.

This invention relates to improvements in heat treating'furnaces of thetype having a vestibule at the discharge end of a horizontal retort, itbeing understood that after the articles have been heat treated in theretort they are withdrawn therefrom into the vestibule preparatory toremoval from the furnace.

The general object of the invention is to provide a furnace `of theVtype indicated that shall have special Vutility in connection withcarburizing operations. j

In the case of metal articles which may be stacked one on top yof theother, for example,

ring gears, it is customary to carburize them in a stacked condition ona tray. However, when it comes to removingsuch articles from thevestibule, they are removed one at a time from the top of the stack andquenched, the removal being through a door at the outer end of thevestibule. When the door is opened -air tends to enter the vestibulewith resultant decarburization and oxidation land cooling of the highlyheated articles. This is most objectionable and it is one of the moreparticular objects of the present invention to prevent such conditionsfrom occurring.

Referring to the accompanying drawings, wherein the preferred form ofthe invention is shown,- Y f Fig. 1 is a vertical longitudinal sectionof the discharge end of the furnace;

Fig. 2 is in part a front elevation and in part a vertical section ofthe construction shown in Fig. l, the section being on line 2-2 of Fig.l;

Fig. 3 is a fragmentary detail section on line 3--3 of Fig. l;

Fig. 4 is a fragmentary detail section on line 4 4 of Fig. l;

Fig. 5 is an enlarged fragmentary detail section on line 5-'-5 of Fig.2, and Fig. 6 is an enlarged section of a yieldable abutment formingpart of the furnace construction.

Letter F indicates the discharge end of a furnace structure which ingeneral is similar to that disclosed in patent to de Coriolis et al.2,033,331 dated March l0, 1936, and which like the patent embodies aprimary heating chamber or retort I4, a secondary heating chamber orvestibule I3, a valve structure II chambers, the valve structureembodying a housing 2l which is anchored in the roof of the furnacestructure, the housing being adapted to receive the valve elements '25and di; when the operating rod 9 for the latter is raised.

As previously indicated, the articles to be heat which separates thetwo' r orrlcE treated will be stacked on trays, one such tray beingindicated at T in Fig. l'with a stack of articles I!) thereon, thearticles being shown in dotted lines. In passing Ythrough the retort I4and into vthe receiving end of the vestibule I3, the trays rest onlongitudinally extending ledges forming part of the floor thereof. Theform of the floor at either side of the Valve structure II is shown inFig. 3, the same comprising two side ledges l5 and IiiV and a -centralledge I6. A tray T is shown as supported on the ledges, it being notedthat central portion of the floor is depressed with reference to itsside portions thereby forming what amounts'to two side channels I1. Thepurpose of these channels is to accommodate tray-pull-out rodsV I8 andI8', one in each channel, each rod having an upturned inner end vI9 forengaging behind the tray to pull it out of the retort I ll into thevestibule I3, and also having an outside hinged handle extension 20.These rods are independently operable from outside of the vestibule, andwhen not in use the hinged extension is disposed as shown in Figs. land2 for reasons presently appearing. Y

TheA outer end ofthe vestibule is closed by a door frame 22. Inasmuch asit is frequently necessary to have ready access to the vestibule, thedoor frame'is shown as clamped to a peripheral flange I3 vof thevestibule by clamps 23. Removably supported on the floor of thevestibule in front of and next to the door frame is a flat toprefractory block 24. This block extends the full width of the vestibuleand is preferably encased by a metal band to protect its top side and toprevent undue wear in handling. That part of the oor on which rthe block24 rests preferably takes the form shown in Fig. 4, the form beingsubstantially the same as shown in Fig. 3, primarily to provide aworking space for the rods I8. The door opening in the door frame 22 isindicated at 26 and it is of slot type with its bottom on a level withthe top of the block 24. The block is as high as possible consistentwith the space required to remove the top article of the stack IIl fromthe vestibule by means of tongs or the like inserted through the dooropening. To insure ample working space above the block, the roof of thevestibule may be stepped upwardly as indicated at 21 for a portion ofits length. The door for the opening 26 is indicated at 28, thesamebeing vertically movable and being normally held tightly closed by anypreferred means as by wedges 29 secured to the outer face of the door,the wedges cooperating with outwardly inclined wedging arms 33 formingpart of brackets 3I secured to the door frame 22.

When a loaded tray T is pulled into the vestibule I3 from the retort I4by the pull rods I8, it is pulled into position next to the inner faceof the block 24 as clearly shown in Fig. 1. In this position, the trayrests on a vertically movable platform or elevator P shown as comprisingthree supporting members or shoes 32 in longitudinal alignment with theindividual ledges I5, I5 and I6 shown in Fig. 3. It will, therefore, beunderstood that when a tray is pulled out of the retort I4, it is pulledinto position on said platform. Ordinarily the stack of articles on thetray will be high enough with respectto the block 24 to permit removalof the first top article by .tongs or the like inserted through the dooropening 26 without raising the said platform,` but if such is.

not the case, the platform is elevated a sufficient distance to permitsuch removal; and such upward movement of the platform `is continued asthe articles are removed one after the otherfrom' the top of the stack.Before describing theV preferred means for elevating the platform, letus briefly consider the advantages of the improved construction thus fardescribed.

After the carburized articles have been moved into the vestibule I3 fromthe carburizing retort I4, itis essential to maintain a carburizingatmosphere in the vestibule' I3 to prevent'decarburization of thearticles, pending Vtheir removal from the latter. To this end, the'vestibule is continuously supplied with a stream of carburizing gas insulcient amounts to' effectively prevent the inow of air through theVdoorv opening 25 when the door 28 is open. This carburizing gas may beintroduced at an appropriate point or points. However, as illustrated inthe drawings, the carburizing gas is introduced through a pair of pipes33 and 33', shown as extending int'o the vestibule below the block 24,the pipes being conveniently disposed in the floor channels at eitherside of the central ledge I6' as showny in Fig'. 4, the discharge end ofthe pipes terminating in relatively close proximity to the` insidevertical face of the block 24. It is. also desirable to prevent thehighly heated articles on the tray from losing heat by radiation throughthe door frame and thisis effectively prevented by the refractory blockZ4.

Leakage of air into the vestibule atV the point |80, (see Fig. 1) wherethe pull rods I8 enter the vestibule is also prevented in a novelmanner, when the rods are not in use. Referringr to Fig. 5 wherein adetail feature of the improvement is shown, l3nt indicates a flangeportion of the vestibule, each rod I8' entering the vestibule through anopening in this flange. Secured to the outside face of this ange is aplate 34 provided with a tapered passage to form a valve seat for acorrespondingly tapered portion 35 of the rod. When the rod is in theposition shown in Fig. 5, it is in retracted or non-use position andwhen `tightly held to its seat inthe plate 34 there will be noinfiltration of air into the vestibule at that point. As previouslymentioned, each rod I8 has a hinged extension 20. When the rod is beingused to pull a tray into the vestibule I3 from the retort I4, theextension will be brought into longitudinal alignment with the otherportion of rod and locked in such position by any preferred means, as bya locking pin passed through both rod portions near the hinge.

When the rod is not being used, said extension is utilized as part ofmeans for holding the valve 35 ofthe rod tightly to its seat in theplate 34 and the manner in which it is so utilized is briefly asfollows. 36 indicates a yieldable abutment secured to the framework ofthe furnace structure. As shown in Fig. 6, this abutment may comprise ahead 31 having a stem 38 which extends into a tube 39, which is anchoredto the framework of the furnace structure as by cap screws 40. One endof a coil spring 4I pressesagainst the inner side of the head,. theother end thereof pressing against a radial abutment 42 securedV to theouter side of the'tube. A nut 43 on the inner end of the stem 38 holdsthe latter in place. The abutment 3S is located below and at one side ofthe point where the rod I8 enters the vestibule. The rod must,therefore, turn on its axis so as to permit the handle portion 20 tocontact the abutment 36 after which the outer end of the handle portionis pushed into locking position with a notched plate 43 secured to theframework of the furnace structure adjacent the side thereof. Thespring' 4I of the abutment'36 is', therefore, under compression andconsequently tends to hold the Valve of the rod I8 tightly to its seat.When the rod` I8 is turned as stated, the hooked portion I9 thereof willbe below' the top side of the li platform P on which the tray T rest inunloading position and, consequently, the rod may be retracted to theposition shown in Fig. 1.

There remains to be described the means for elevating the platform P.

It maybe stated at the outset that it is of more or less secondaryimportance whether the platform be elevated by lifting rods extendingupwardly through the roof of the vestibule or by push rods extendingthrough the floor of the vestibule. tion is preferred and is the onechosen for illustrative purposes.

Extending crosswise beneath the furnace structure is a relatively narrowtank 53 adapted to contain a sealing liquid such as oil. In this tank isa cross beam 5I which is suspended from above by side rods 52 and 52',the upper end ofthe rods being in the form of a rack 53 for engagementwith a pinion 54 on a drive shaft 55, the shaft being turned by anypreferred mechanism as by a hand operated hoist whereof the pull chainis indicated at 55. Supported by and extending upwardly from the crossbeam 5I are three push rods 5l, one for each platform shoe 32,

the rods extending through tubes 58 which are supported by and extenddownwardly from the floor of the vestibule to a point below the level ofthe liquid in the tank 53, the shoes 32 being xedly secured to the upperend of their respective rods 5l. is, of course, to prevent infiltrationof air into the vestibule by way of the lifting rod passages.

What I claim is:

l. In a heat treating'furnace having a chamber wherefrom articles in astack on a tray are required to be removed, the combinationcompris-inge. block of substantial height positioned within andextending across and substantially filling the discharge end of thechamber except at the upper portion thereof, a closure at the '7discharge end of the chamber having a door opening which provides accessto said upper portion, a platform normally disposed adjacent the floorof the chamber in front of said block for receiving a tray which is tobe unloaded, and

means for elevating the platform to bring the top article of the stackon the tray into position for removal from the chamber across the top ofsaid block as the articles are successively removed from the top of thestack.

The latter construc- The purpose of thetubesy 58 t holding chamber, arod in the chamber for mov-v 2. In a heat treating furnace having achamber wherefrom articles in a stack on a tray are required to beremoved, the combination comprising a block of substantial heightpositioned Within and extending across and substantially filling thedischarge end of the chamber except at the upper portion thereof, aclosure at the discharge end of the chamber having a door opening whichprovides access to said upper portion, and vertically movable meansnormally disposed adjacent the floor of the chamber in front of saidblock and adapted to engage a tray from beneath for elevating the trayto bring the top article of the stack on the tray into position forremoval from the chamber across the top of said block as the articlesare successively removed from the top of the stack.

3. A heat-treating furnace having a work-holding chamber, a rod in thechamber for moving a body in the chamber, a wall having an openingthrough which the rod extends out of the chamber, a valve on said rodadapted to form a gastight closure between the rod and said wall atlsaid opening, a handle extension hinged to saidrod at such a point thatwhen the valve on the rod is in engagement with said wall the hinge willbe outside of the'chamber, an abutment against which the said extensionmay be fulcrumed to exert outward pull on the rod when the valve on thelatter is in engagement with said wall, and means remote from saidabutment for releasably holding the extension in position against theabutment.

4. A. heat-treating furnace having a Workholding chamber, a rod in thechamber for moving a body in the chamber, a wall having an openingthrough which the rod extends out of the chamber, a valve on the rodadapted to form a gas-tight closure between said rod and said wall atsaid opening, and means for holding said valve against said wall at saidopening when the rod is not in use.

5. A heat-treating furnace having a working a body in the chamber, awall having an opening through which the rod extends out of the chamber,a valve on the rod adapted to form a gas-tight closure between said rodand said wall at said opening, a handle hinged to the outer end of saidrod, and means adapted to cooperate with said handle to hold said Valveagainst said wall at the opening when the rod is not in use.

6. In a heat-treating furnace, means including a floor, roof, side wallsand an end wall forming a Work-holding chamber, said end wall having anopening a substantial distance above said floor, and means including anelevator in said chamber and a shelf between the elevator and saidopening for making the Work in the chamber accessible for removal fromthe latter through said opening.

'7. In a heat-treating furnace, means including a floor, roof, sidewalls and an end wall forming a horizontally-extending work-holdingchamber, said end wall having a work-discharge passage a substantialdistance above said floor, an elevator in the chamber and whose normalposition is adjacent said floor, and a pull rod between said floor andelevator and adapted to be manipulated from the outside to pull a loadof work along said floor on to the elevator.

8. The combination with a furnace chamber wherefrom articles arerequired to be removed from a stack adjacent the discharge end of saidchamber, of a wall forming a closure at the discharge end of saidchamber, a stack-elevating means within said chamber in spaced relationwith respect to said wall, a heat-insulating block arranged between saidmeans and said wall and substantially filling the lower half of saidchamber, and said wall having a relatively restricted, normally closeddoorway in communication with the the upper portion of said chamber, thearticles being removable through said doorway.

ERNEST G. DE CORIOLIS.

